lower.to.upper.tri.inds {cluster} | R Documentation |
Compute index vectors for extracting or reordering of lower or upper triangular matrices that are stored as contiguous vectors.
lower.to.upper.tri.inds(n) upper.to.lower.tri.inds(n)
n |
integer larger than 1. |
integer vector containing a permutation of 1:N
where
N = n(n-1)/2.
these functions are mainly for internal use in the cluster package, and may not remain available (unless we see a good reason).
upper.tri
, lower.tri
with a related
purpose.
m5 <- matrix(NA,5,5) m <- m5; m[lower.tri(m)] <- upper.to.lower.tri.inds(5); m m <- m5; m[upper.tri(m)] <- lower.to.upper.tri.inds(5); m stopifnot(lower.to.upper.tri.inds(2) == 1, lower.to.upper.tri.inds(3) == 1:3, upper.to.lower.tri.inds(3) == 1:3, sort(upper.to.lower.tri.inds(5)) == 1:10, sort(lower.to.upper.tri.inds(6)) == 1:15)